This disclosure is directed to systems and methods for improving produced and/or reproduced images deposited on output image receiving media in image forming devices.
Image forming devices are necessary productivity tools for producing and/or reproducing documents in ever-broadening applications in business and personal uses. With the proliferation of image forming devices, a requirement for processing very complex image data in order to produce and/or reproduce higher-quality images on virtually any image receiving medium has arisen. Characteristics of various image receiving media that may affect output image quality, requiring adjustment within image forming devices, include variations in medium thickness, quality, and composition, and wide variance in the content of the materials from which various image receiving media are formed. The requirement for a specific image forming device to be able to accommodate image receiving media of varying characteristics without degradation in produced and/or reproduced image quality is an imperative. Varying technologies are available to address image quality levels as they relate to varying characteristics in image receiving media.
A specific example to highlight the need to be able to adjust print characteristics to characteristics associated with a particular output image receiving medium regards printing on a lightweight output image receiving media.
Printing on lightweight media is a commercial necessity in order to produce books, magazines and other forms of documents that can be maintained at archives and in libraries in an economized storage space. The use of lighter weight i.e., reduced thickness, image receiving media may advantageously result in a number of benefits including an overall cost reduction associated with, for example, shipping and storing printed materials associated with such media, among others.
Particularly in electrostatic image forming devices, when printing on lightweight output image receiving media, characteristics of the individual receiving medium can have significant effect on the image quality of the processed output image in the image forming device. Among the characteristics that are particularly acute when dealing with lightweight output image receiving media are, for example, moisture content and an ability to maintain adherence of the lightweight output image receiving medium, for example, to image receiving media handling paths within the image forming device in order to attempt to ensure that the lightweight output image receiving medium, for example, fully conforms to the photoreceptor device. In this regard, particularly with respect to lightweight output image receiving media, it is necessary to ensure a flattening of the lightweight output image receiving media to provide proper support for the transfer process. Lightweight output image receiving media distorts very easily, and more so, for example, when it has been exposed to moisture. Such distortion may render an individual lightweight output image receiving medium very difficult to accurately deposit an output image on without at least some distortion in the output image. Additionally, given the presence of electrostatic forces between the lightweight output image receiving medium and the photoreceptor surface, individual sheets of lightweight output image receiving medium have difficulty in sliding smoothly to conform precisely to the surface of the photoreceptor. In order to improve the quality of produced and/or reproduced output image deposition on, for example, lightweight output image receiving media, therefore, flattening is essential.
In applications like lightweight media printing (LWP), the flatness of the media is highly sensitive to the environmental conditions. Due to high ambient temperature and humidity, the LWP media absorbs moisture at a high rate and tends to ripple or buckle around the edges. The image formation process with respect to such LWP media is therefore, compromised. This is particularly true if the LWP medium is exposed to an environment >55 GOW, which is a combination of high temperature (>70 deg. F.) and a high relative humidity (>55%), over a period of time exceeding several hours. When LWP media, in that state, is fed to a machine and is moving through the transfer zone, high tacking forces at the lead edge are imparted by transfer process current. Those tacking forces are further exacerbated by voltage levels in non-imaged areas due to the cleaning fields that the control system must operate at depending on the material conditions. The higher the tacking force, the less able the media is to move around, yield to transfer assist blade (TAB) force to flatten ripples, and fully conform to the photoreceptor device. Because the LWP medium is not able to conform to photoreceptor device, the non-uniformities in the LWP medium will end up appearing as deletions in the body of the LWP medium.
Other effects of the electrostatic image forming process are that when the lightweight output image receiving medium, particularly in high moisture content environments resulting in elevated moisture absorption tending to ripple and/or buckle around the edges, is moving through the transfer zone in an electrostatic image forming device, high tacking forces at the lead edge are imparted by the transfer process current. Those tacking forces may be further increased by voltage levels in non-imaged areas due to a number of effects, such as, for example, the relative strength of a cleaning field that the control system of the electrostatic image forming device introduces based on material conditions. Elevated tacking forces at the edges result in particularly lightweight output image receiving media being unable to conform to the appropriate surfaces in the image receiving media handling paths within the image forming device. As such, formed ripples and/or buckles are not afforded an opportunity to be flattened in order that the output image receiving medium can filly conform to the contours of the photoreceptor device. If such an output image receiving medium is not able to conform to the contours of the photoreceptor device, ripples and non-uniformities in the output image receiving medium will tend to gather and merge together creating potentially large deletions in the body of the medium. Such deletions may most predominantly appear as a single main deletion area in the center of the individual sheet of output image receiving medium. Any distortion in the output image receiving medium will, therefore, tend to result in reduced image quality in the images produced and/or reproduced by the image forming device.